1. Field of the Invention
The present invention relates to a circuit device for driving a droplet ejection head that ejects droplets to form an image, and a droplet ejection apparatus on which the circuit device is mounted.
2. Description of the Related Art
Widely-known schemes for ejecting ink adopted by print-on-demand inkjet heads (droplet ejection heads) include a scheme that uses a piezoelectric actuator or the like and a scheme that uses a heating element that generates heat when electric current flows therethrough. The former scheme is carried out by arranging a diaphragm in a portion of a wall of a liquid chamber filled with ink (droplet) and displacing the diaphragm using the piezoelectric actuator or the like to increase a pressure in the liquid chamber, thereby causing the ink to be ejected. The latter scheme is carried out by arranging the heating element in a liquid chamber filled with ink (droplet) and increasing a pressure in the liquid chamber with an air bubble generated by heat from the heating element, thereby causing the ink to be ejected. Inkjet recording apparatuses (printers) are used by a large number of people in diverse applications because inkjet recording apparatuses (droplet ejection apparatuses) that include such inkjet heads as described above become increasingly less expensive and enhanced in image quality, and also because personal computers (PCs) have become widespread in homes.
In recent years, there are demands for miniaturization of printers and functional enhancement in performance of a driver integrated circuit (IC) as print speeds of inkjet recording apparatuses increase. In particular, the performance of a driver IC affects not only performance of the apparatus but also manufacturing cost of surrounding associated parts.
Under the circumstances, an integrated circuit device and electronic equipment including an interface circuit that allows mount of a component and the like on any one of a front surface and a back surface of a substrate are disclosed in Japanese Patent Application Laid-open No. 2007-258718, for example. This integrated circuit device is configured such that terminals are arranged in line symmetry with respect to a center axis of the terminal array, and a driver IC is mounted on a selected one of the front surface and the back surface of the substrate.
Some of shuttle-type inkjet recording apparatuses include a drive circuit on an apparatus body to minimize the weight of a movable unit of the inkjet recording apparatus to achieve a higher print speed. In this case, it is required to arrange, on the movable unit, a relay board that connects between the apparatus body and the movable unit to transmit input signals generated by the drive circuit on the apparatus body to the movable unit. In a case where a driver IC of a single type is used to drive multiple heads (droplet ejection heads), wiring on the relay board is generally complicated, which undesirably arises the need of employing a multi-layer circuit board. This is because the number of input signal lines has increased in recent years to implement complicated driver IC control.
The integrated circuit device disclosed in Japanese Patent Application Laid-open No. 2007-258718 achieves miniaturization by allowing mount of a component and the like on any one of the front surface and the back surface of the substrate on a signal-receiving side. However, the integrated circuit device disclosed in Japanese Patent Application Laid-open No. 2007-258718 relates to the configuration of the substrate on the signal-receiving side itself but does not simplify the configuration of a circuit board, such as the relay board described above, on a side from which input signals generated within the apparatus body are transmitted.
Therefore, there is a need for a circuit device and a droplet ejection apparatus capable of simplifying a layer structure of a circuit board on a side from which input signals are to be transmitted to reduce manufacturing cost.